Nemesis Sub-Terra is located in the Forbidden Valley section of Alton Towers Resort in Staffordshire, England. This attraction is an indoor "psychological" drop tower dark ride that serves as an expansion of the lore surrounding the iconic Nemesis Reborn roller coaster. It is situated in the building that formerly housed the "Dynamo" ride, near the entrance to the Forbidden Valley area and close to the Galactica (formerly Air) roller coaster. After being closed for several years starting in 2015, the ride underwent a significant refurbishment and officially reopened to the public in May 2023. The experience is themed around a military research facility run by "The Phalanx," a shadowy organization investigating a mysterious alien egg found underground. Because it is an indoor, enclosed attraction, it is often a popular choice during the park's Scarefest events or on rainy days. To find it, guests should head toward the back-right of the park (from the main entrance) following the signs for Nemesis; the Sub-Terra building is easily recognizable by its military-green exterior and the presence of "Phalanx" guards stationed outside.